The present invention relates to the structure of a choke coil for high-frequency power use and which is suitable to make the coil more compact and thinner.
The requirements in development for more compact and thinner electronic apparatus for switching power and the like have been continued as they are directly linked to the requirement for more compact electronic parts.
In particular, there is a great demand for more compact choke coils which are one electronic part which requires a particularly large area.
So far, choke coils have been designed with regards to the ease of manufacture of the product, and efficient combinations of a core and a coil within a predetermined volume.
FIG. 8 is a partial sectional view of a conventional choke coil, and shows a general configuration where a wire member 22 is wound around a bobbin 21 into which a core 20 is inserted, and where the ends of a wire member 22 are connected to the terminal pins 23.
This structure is easy to manufacture but it makes gaps between the wire members and so the volume of the wound wire member, that is, the coil becomes large.
FIG. 9 is a partial sectional view of a different type of conventional choke coil, and where a band-shaped conductor 32 is wound around a bobbin 31 into which a core 30 is inserted, and separate leads 33 electrically connected to the band-shaped conductor 32 are connected to terminal pins 34 provided to the bobbin 31.
A structure, where a band-shaped conductor is wound, has the advantage of having a smaller volume for the wound coil, compared with a structure where a wire member is wound. The band-shaped conductor 32 is connected to a terminal pins 34 via leads 33 and so connecting the leads 33 involves a connection process using either soldering or welding to the band-shaped conductor 32, and so there is room for improvement as far as ease of manufacture is concerned.
Conventional choke coils have various technical problems as described above, and are unsuitable as regards making the coil more compact, thinner and easier to manufacture.